Electrical shocking devices have been previously proposed for use on bird feeders. For example, U.S. Pat. No. 5,285,747 provides an electric shock, but in order to be shocked the pest must touch two perches that are spaced vertically from one another by a substantial distance. If the pest does not touch both perches simultaneously, it will not receive a shock.
U.S. Pat. No. 5,150,665 also has a pair of vertically spaced apart conductors, one of which must be touched by a squirrel's front feet and one by the squirrel's rear feet. It is unlikely that a squirrel will invariably assume this position. Consequently, the device will not be consistent in deterring pests.
U.S. Pat. No. 2,856,898 describes an animal-proof bird feeder with a coil spring mounted around a support rod that allows one contact to rub over serrations on another contact to make and break a primary circuit for shocking a pest. I have found that electrical components such as contact points and other moving parts can rust or corrode over time, particularly from adverse weather conditions including rain, snow and sleet. It will also be noted that the patented bird feeder requires a special bird feeder design having support spring, rod and contact points at the top with a battery casing below it. Consequently, the patented bird feeder has to be specially constructed and is not suited for use in a variety of tray-style bird feeders already on the market.
In view of these and other deficiencies of the prior art, it is one object of the present invention to provide a compact self-contained pest deterrent device for a tray-style bird feeder that is small in size and can be mounted unobtrusively on a wide variety of tray-style bird feeders already in use and on the market, i.e., one that is suited for being mounted upon existing tray-style bird feeders as a retrofit unit or mounted at the factory by the manufacturer of any of a variety of tray-style bird feeders now being manufactured and sold by various producers without having to change the design of the feeder except for the manner in which it is supported.
Another object is to provide a pest deterrent device for a tray-style bird feeder that is more positive acting in the sense that it will much more reliably give a harmless shock to a pest but will not shock birds.
A further object is to provide a device of the type described that is not subject to corrosion or other damage and will remain highly effective in operation even though exposed to adverse weather conditions including snow, sleet, rain, etc.
A further, more specific object is to provide an improved pest deterrent of the type described that is compact, self-contained, rugged in construction, relatively inexpensive and adapted to produce a powerful but harmless shock that will reliably shock a pest but at the same time provides dual protection for birds by (a) locating conductors away from where birds normally perch and (b) having a provision for preventing birds from turning on the current.
These and other more detailed and specific objects of the present invention will be better understood by reference to the following figures and detailed description which illustrate by way of example but a few of the various forms of the invention within the scope of the appended claims.